2003 A4 1.8t Q Tiptronic.

I'm about to order a K04-015 turbo, and while I'm in there I was thinking about boosting performance by upgrading either:

- Downpipe
- Turbo manifold

Which will give me the most bang for the buck? Future mods will include chip, exhaust.

PS: Would either/both these changes impact emissions? This is a daily driver.

 

i have the same car, also my daily driver so +1 for this thread ha

 

I'd skip the k04 and go bigger if you're choosing to do this. If you blew the k03 and found it as a replacement, then so be it. But spending money on a straight k04 build is probably going to disappoint you. You should start with a chip and DV, then exhaust, and go from there. Turbo before chip is like wiping before you poop. Read the FAQ sticky in the B5 section - 95% of the info applies to the B6 as well.

 

I bought the car with 69,000 miles, and the original turbo was on the brink (almost no boost, horrible whine). It died 3 days after I bought the car. The dealer/broker replaced it for free, but with a Chinese K03 turbo, which works but whines and I wouldn't want to ask much more from it by chipping the car. Maybe I'm mistaken in that concern? My research has led me to believe the K04 is a better platform for future mods/chipping than the K03.

I now have 10,000 miles on the Chinese turbo, and the car seems otherwise stable, so I'm feeling ready to upgrade the turbo without worrying that the original turbo died due to something wrong with the car.

Regarding BT, I read a lot about the Garrett turbos, but most of them seemed like much bigger "projects" -- not straightforward direct bolt-ons -- and the most affordable option costs 2x as much as a K04-015.

This AudiZine thread (link) is very informative, and it looks like the GTRS Elim is a straight bolt on and can be had for around $1,525. Still, that's $700 more than a K04-015.

GTRS Elim Advantages: Eliminates torque spike, smoother power delivery across band once turbo boost begins

GTRS Elim Disadvantages: Slower spool up than K04, maybe need intercooler? Significantly more expensive.

So, let's say I consider the GTRS. Is there anything else I need to worry about before I drop $1600 into it? The FAQ says "you will need":

- Injectors ($300+)
- MAF ($???)
- Adjustable FPR ($100)
- Manual Boost Controller ($100)
- Exhaust ($1,000+)
- Intercooler ($300)
- Turbo Inlet Pipe ($150)

However, it doesn't say which of these additions are required, vs. desirable. Can you just bolt on the GTRS and then add these other elements over time?